Must have been before “my time”…
This Lycoming has ~1400hours on it, in a ca. 2005 C172 (non-turbo).
Three pots are off for corrosion inspection (national AD).
So the idea is to continue to check the oil filter for metal, perhaps measure valve travel periodically? (How is that done? With a “measuring clock”?)
Would there be any point in running with Cam Guard in the future, is it too late anyways?
Also, Michael would disregard oil analysis (as always), while others would recommend trending the oil to look for metal. Not sure what to do on this one….
G
Oil analysis, cutting the filter and inspecting the strainer are standard techniques. Oil analysis is so cheap that it’s not a big thing. What Michael rightfully complains about is that oil analysis does not tell you what to do, it’s just one tool and there are many ways to interpret a result.
Lycoming has a SB that details the valve travel measurement. That’s definitely in order in your situation but’s entirely trivial. Remove the rocker covers, attached the “measuring clock”, turn the prop and write down the value. Do that every 100h and you can see your lobe size.
It’s true that almost nobody would open up an engine just because some metal goes up on the oil analysis from say 10ppm to say 30ppm IF the oil filter and the oil strainer are clean AND you are 100% sure the maintenance company is actually examining them (many don’t).
The cost of opening up an engine, even if you don’t do anything with it, would be of the order of €5000 so is not to be undertaken lightly. And if anything is found which makes it unairworthy (any of a hundred different things) no engine shop (that isn’t a complete cowboy) will put it back together until the said issue has been rectified, so the likely bill is going to be way more than €5000.
Camguard does help a lot with wear reduction. It is perhaps the only additive which actually does anything.
This is also worth a read. You need to stick with the same lab.
Peter wrote:
ou are 100% sure the maintenance company is actually examining them (many don’t).
If I were an owner I would DEMAND to see the open oil filter, better yet, have it opened and examined while watched !
re: Measuring cam lift from the rockers : Unfortunately, this technique is not very reliable since the hydraulic cam followers can ’deflate" giving you a false positive.
I’ve said it before and I’ll say it again: the best way to monitor cam/follower wear is from collecting regular (every 25 – 50 hours) oil filter samples.
